When i turn the air on hot air comes out the vents what should i look for to solve this the air worked a month ago.

 

Get out your owners guide and start checking some fuses. I'm thinking (though I could be wrong) that maybe the compressor is not kicking on. There could be a few fuses that control this, but usually only one of those fuses would be bad. There is one fuse panel underneath the drivers side dash, and one under the hood on the drivers side just in front of the brake booster (called the power distribution box). The best way to tell if your compressor is/is not kicking on would be for you to start the vehicle, lift the hood, and have someone else to get in the vehicle and simply turn on/off the A/C, and listen for the compressor to "click". You have to put the switch in one of the A/C modes (max a/c or normal a/c) in order to hear this. If you don't hear it, then you might have a bad fuse. Your owners guide has a section on which fuses control which functions. However, if you do hear the compressor come on, then you may have lost your freon. This problem is more costly.

Good luck

 

By the way, I just noticed you are reporting this problem on your F250. I'm sure there are diiferences as to which fuses control the A/C compared to the F150. I'm sure someone else on this forum could be a little more knowledgeable than me about the fuses.

Good Luck again

 

The compressor is working is there a valve that controles the air and heat.

 

The heat selector switch on the dash may be the problem. These are vacume switches and crack after time. Try pushing in on the switch and turning it slowely to the cold air side. Do this a few times and see if it works. I had this problem on my 99. You may also not be getting any vacume to the switch.

 

A f250 LD is the same truck as a F150 7700. Ford changed the name around 99.